Electrochemical electrode structure



De 18, 1952 F. soLoMoN ETA.

ELECTROCHEMICAL ELECTRODE STRUCTURE Filed May 26, 1958 2 sheets-Shen 1 F RANK SOLOMO'N KENNETH N. BROWN REMA'O Dl PASQUALE INV ENTORS.

Dec. 18, 1962 F. soLoMoN ETAL 3,069,486

ELECTROCHEMICAL ELECTRODE STRUCTURE Filed May 26, 1958 2 Sheets-Sheet 2 FN( SLOM/V KENNETH M BROWN EM' D/ PASQUALE INVENTORS.

BY M

AGE/vr :Manasse ELECIRQHEMECAI. ELiIClli-E STRUCTURE Frank Solomon, Great Neck, Nft., and Kenneth N.

Brown, Teaneclr, and Renato Di Pasquale, Rutherford, NJ., assignors to Yardney International Corp., New York, NY., a corporation of New York Filed May 26, 1953, Ser. No. 737,567 Claims. (Cl. 13e-uw) ,improved-high-rate batteries and special electrode assemblies for such batteries.

It is a further object of this invention to provide a composite electrode assembly containing zinc as an active material and yielding higher discharge rates heretofore than conventional electrodes of similar weight containing sheet zinc.

Still another object is to provide a zinc-electrode assembly for alkaline accumulators which maintain its excellent discharge rate and capacity over a large number Vof charge cycles.

The above objects are achieved by a composite electrode assembly made up of several layers of expanded active metal, preferably having one or more sheets of anonconductive, permeable or semi-permeable electrolyte-storing material sandwiched therebetween, which are joined together (eg. at marginal zones beyond the periphery of the electrolyte-permeable sheet material) by a thermal bond under pressure and heat at a temperature below the melting point of the metal. In addition, the layers of Zinc or other metal are preferably positioned in a certain specic relationship to insure maximum access of the electrolyte to the active material.

Under some circumstances, the electrode structures according to the invention would normally have, because of their large surface area, an excessive tendency to react with the electrolyte on open circuit and to polarize at high discharge rates. This can be remedied by a controlled amalgamation of the active material.

The invention will be further described with respect to the accompanying drawing wherein:

FIG. 1 is a plan view of a laminated structure according to this invention;

FIG. 2 is a perspective view of this structure before final assembly, illustrating several layers of expanded metal interleaved with sheets of irrigating material;

FIG. 3 is a fragmentary view of some of the expanded metal layers forming part of an electrode embodying this invention, with the intervening non-conductive layers removed;

FIG. 4 is a plan View (parts broken away) of a moditied electrode according to this invention; and

FIG. 5 is an enlarged cross-sectional view taken along line 5-5 of FIG. 4.

Referring to FIGS. 1 and 2, the laminated electrode 100 comprises several expanded-metal layers 101 obtained by perforating and stretching at sheets of zinc or other electrochemically active material. These layers are fusion-bonded along a marginal zone 103, and at intermediate zones 104 of limited extent, to one another and to a States are if. Q@ dddfid@ Patented Een.. 18, 1952 centrally positioned grid 192 having leads 105 secured thereto by welding or other means; grid 102 may be of copper, silver or any other highly conductive, relatively inert metal in sheet, mesh, mat or other suitable form.

interposed between the several layers of expanded metal 101 and the conductor 162 are electrolyte-storing layers 2&3 of permeable or semi-permeable, non-conductive material such as paper, regenerated cellulose, cellophane, polyvinyl-alcohol film, wooden plaques, fiberglass or nylon mesh. The conductive layers 101 and 1tl2 project beyond the edges of storage layers 21B and the latter are provided with cutouts 24 to allow for free contact of the metallic elements in order to permit the formation of the marginal and internal zones 103, 104 of thermal fusion by which the layers 203 are locked between the sealed layers 1411 of expanded metal and the conductor 102. By virtue of the presence of the electrolyte-storing, irrigating material 263 within the body of the electrode Idil, large volumes of electrolyte are maintained in close contact with and immobilized at the active faces of the electrode, independent of any position which the battery may assume; the electrolyte-permeated material 203 further serves to keep the active faces of the electrode cool and wet even during discharge of cells at high-discharge rates, eg. where the entire useful capacity is to be drained in an interval of one minute.

The joining of the layers 1191 of expanded metal to the conductor 102 and to one another is best achieved by low-temperature bonding. When the active metal is zinc, pressures of 30-150 kg./cm.2, applied for a few seconds with temperatures ranging from to 375 C., form a homogeneous seal at zones 193 and 1114. These temperatures, while being below the melting point of the active metal, are high enough to decompose surface oxides which would interfere with the bonding. The homogeneous seal so formed allows the bonding zones 163, 104 of the active layers to continue as chemically active areas, thereby permitting high current rates by insuring intimate contact between the active material and the conductive grid 192. The intermediate sealed areas 194 further serve to prevent shifting and buckling of the electrode layers during high-rate discharge. I

FIG. 3 shows the lattice arrangement of a number of relatively staggered expanded-metal sheets 101e, 101]), ldlc forming part of the electrode 1612'. The staggered sheets of expanded metal have a very large effective surface area and, unlike electrodes made from compacted comminuted particles, provide easy electrolyte access while not being polarized by the accumulation of dissolved discharge products or cell gases.

The interstices of the expanded metal may be filled with a paste of Zinc oxide and/ or metallic zinc powder or other active metal in comminuted form. This powder may be reduced in situ by conventional electroforming, electrolytic charging or dry-charging procedure. The advantage of adding such comminuted material is that it provides a reservoir of easily activated metal to maintain the capacities of the cells during extended cycling.

A further embodiment is shown in FIGS. 4 and 5 in which the expanded-metal layers 101 have been replaced by laminated sheets 401 to form an electrode 4111). Sheets 461 are slitted lby roll-shearing and bending operations to form a network of parallel, grooved metallic filaments providing triangular and trapezoidal electrolyte retention channels 432', 402 as well as Slots 403 as shown in the cross-sectional view of FIG. 5. Adjacent corrugated metal layers dela, 41PM, 461C are positioned at right angles to one another and are interleaved with irrigating membranes Ztl in the manner described above with respect to layers 101. As the electrolyte contacts the lilaments of each layer 461 of the electrode 400, the liquid spaanse I3 accumulates in the channels 402', 482" and is distributed along the entire surface face of each electrode layer.

Because of the large surface area offered by the electrode, there exists a marked tendency for an electrode to react with the electrolyte on open circuit and to polarize at high discharge rates if the entire material of layers 191 or 401 is zinc. By treating the assembled electrode with a solution of mercury salts, an amalgam containing 0.035i0.(}15%, by Weight, of mercury is deposited on the Zinc. The presence of the amalgam controls the evolution of hydrogen gas at the electrode during highrate discharge and thereby permits full access of the electrolyte to the electrode. lt is of course understood that the mercury is reduced in situ on the Zinc in Varying amounts, regions of highest activity reducing the greatest amounts of mercury.

The above invention may be realized in a number of Variations, which will be apparent to those skilled in the art within the scope of the following claim.

We claim:

l. An electrode assembly for electrochemical cells comprising an assembly of multiple layers of perforated zinc material and at least one layer of a more highly conductive metal capable of functioning as a collector of electricity, the perforations in said zinc material extending through the thickness thereof whereby liquid electrolyte may pass therethrough and be stored therein, non-conductive electrolyte-permeable material disposed between layers of said metallic materials, said non-conductive material extending across only a portion of the surface area of said metallic layers and leaving a substantial peripheral zone of metal which extends beyond the margins of said non-conductive material whereby said metallic layers are in electrical Contact with each other, said metallic layers being bonded together along a substantial area of said peripheral Zone which forms a seal that encloses said non-conductive material.

2. An electrode assembly according to claim 1 wherein the zinc is amalgamated.

3. An electrode assembly according to claim 1 wherein said layer of highly conductive metal is selected from the class consisting of perforated copper and silver material.

4. An electrode assembly according to claim 1 Wherein said non-conductive permeable material is selected from the group consisting of regenerated cellulose, paper, polyvinyl alcohol lrn, Wooden plaques, berglass and nylon mesh.

5. An electrode according to claim 1 including electrolyte-retaining channels disposed adjacent said perforations in said Zinc material.

References Cited in the file of this patent UNITED STATES PATENTS 504,455 Reed Sept. 5, 1893 519,602 Elieson May 8, 1894 624,230 Marquand May 2, 1899 1,055,221 Piotrowski et al. Mar. 4, 1913 1,376,566 Murphy May 3, 1921 2,923,170 Haunz Dec. 3, 1935 2,375,211 Brennan May 8, 1945 2,463,565 Ruben Mar. 8, 1949 2,527,576 Ruben Oct. 3l, 1950 2,684,396 Barrett July 20, 1954 2,780,062 Schlecht et al. p Jan. 18, 1955 2,776,331 Chapman Ian. l, 1957 2,830,108 Peters Apr. 8, 1958 2,833,847 Salauze May 6, 1958 2,867,678 Doyen Jan. 6, 1959 FORElGN PATENTS 23,489 Great Britain 1897 

1. AN ELECTRODE ASSEMBLY FOR ELECTROCHEMICAL CELLS COMPRISING AN ASSEMBLY OF MULTIPLE LAYERS OF PERFORATED ZINC MATERIAL AND AT LEAST ONE LAYER OF A MORE HIGHLY CONDUCTIVE METAL CAPABLE OF FUNCTIONING AS A COLLECTOR OF ELECTRICITY, THE PERFORATIONS IN SAID ZINC MATERIAL EXTENDING THROUGH THE THICKNESS THEREOF WHEREBY LIQUID ELECTROLYTE MAY PASS THERETHROUGH AND BE STORED THEREIN, NON-CONDUCTIVE ELECTROLYTE-PERMEABLE MATERIAL DISPOSED BTWEEN LAYERS OF SAID METALLIC MATERIALS, SAID NON-CONDUCTIVE MATERIAL EXTENDING ACROSS ONLY A PORTION OF THE SURFACE AREA OF SAID METALLIC LAYERS AND LEAVING A SUBSTANNTIAL PERIPHERAL ZONE OF METAL WHICH EXTENDS BEYOND THE MARGINS OF SAID NON-CONDUCTIVE MATERIAL WHEREBY SAID METALLIC LAYERS ARE IN ELECTRICAL CONTACT WITH EACH OTHER, SAID METALLIC LAYERS BEING BONDED TOGETHER ALONG A SUBSTANTIAL AREA OF SAID PERIPHERAL ZONE WHICH FORMS A SEAL THAT ENCLOSES SAID NON-CONDUCTIVE MATERIAL, 